Cannabis is the world's most popular illegal drug, but what does it do to your brain and, more importantly, will it be funny to see Jon Snow get high?

Drugs Live (Channel 4) arranged for some people to smoke hash, and the far stronger skunk, in a carefully controlled experiment and their brains would be monitored throughout.

Strangely, the participants were eminent, posh, middle-class people: former BBC Royal Correspondent, Jennie Bond, journalist and former Tory MP, Matthew Parris, a doctor, a former detective and Jon Snow himself. But does this privileged group represent typical cannabis users, or do they even represent the population as a whole? Obviously not, but they're probably more coherent than a bunch of stoned students, and therefore better subjects for a televised trial. I suppose it may also have seemed slightly unethical to feed cannabis to young people, even if it was being done in the name of scientific research.

The cameras eventually moved away from the middle-class sorts and filmed 'ordinary' people talking about their cannabis use but it was the usual assortment of grubby student types giggling about how they loved 'stoned sex'. And when the audience were questioned, it was to speak with cliched 'stoners' about how much they liked chilling out to music when smoking cannabis. There was a huge gulf between the experiments' participants and 'ordinary' people.

So the main attraction for me was the chance to see Jon Snow stoned. His experience seemed quite funny: he was spaced out and weird in a fluffy blue jumper and he started hugging the doctor, but he soon became distressed. 'I felt that somehow my soul had left my body,' he said and considered the skunk he took to be 'aggressive filth'.

We were then given a laidback, humorous history of cannabis, including the interesting little snippet that the new breed known as 'skunk' was so-called because of its horribly strong smell. The drug was brought in from Mexico and Afghanistan till the San Francisco hippies of the 70s learned how to grow their own, and then the availability of cannabis seeds and high-strength lamps meant some rebels could even grow it in their attics and cupboards. The cartoonish tone of this history segment made it clear Channel 4 didn't see cannabis as an appalling, dangerous drug.

Professor David Nutt, the former Government adviser on drugs, was on hand with a gigantic model of the brain to show what the cannabis was doing to the participants' perceptions and memories. He reiterated his controversial view that alcohol is the most dangerous of all recreational substances. We saw his 'Harm Index' which put booze ahead of notorious things like crack, meth and cocaine, and far ahead of cannabis. He was sacked by the Government for those views, but Channel 4 were clearly more imaginative and less repressive than our wise masters in Parliament.

The main findings of the trial (the trial of nice, middle-aged people) seemed to be that cannabis makes music feel more pleasurable but can also push you into anxiety and paranoia, and you should avoid it as a youngster when your brain is still developing. Well, those were hardly revelations, were they? It may have been good to have them cemented in scientific fact, but surely everyone knew those things via anecdotal evidence?

The progamme was starting to falter until Colorado was mentioned. Colorado has been brave enough to legalise the drug and the Rockies haven't tumbled down and crushed everyone, so should Britain try it? This debate was the best part of the shoe, but was shoved into the final ten minutes.

My own conclusion was that cannabis should obviously be legalised. I'd feel perfectly safe walking down Sauchiehall Street on a Saturday night if everyone was stoned instead of drunk, boaking in the gutter, kicking bins off lampposts, swinging punches and clogging up the A+E departments. Drink is more dangerous and more damaging. There's no logic to keeping cannabis illegal whilst supermarkets are practically giving alcohol away. It's like saying daggers, machetes, swords and bayonets are legal, but, by God, you'd better not try and buy tacks!